Products having high wear-resistance are extensively used and there is a constant need for less expensive products having the same or better performance as/than existing products.
The manufacture of products having high wear-resistance may be based on e.g. powders, such as iron or iron-based powders, including carbon in the form of carbides.
Generally, carbides are very hard and have high melting points, characteristics which give them a high wear resistance in many applications. This wear resistance often makes carbides desirable as components in steels, e.g. high speed steels (HSS), that require a high wear resistance, such as steels for drills, lathes, valve seats, and the likes.
Examples of conventional iron-based powders with high wear resistance are disclosed in e.g. the U.S. Pat. No. 6,679,932, relating to a powder mixture including a tool steel powder with finely dispersed carbides, and the U.S. Pat. No. 5,856,625 relating to a stainless steel powder.
W, V, Mo, Ti and Nb are strong carbide forming elements which make these elements especially interesting for the production of wear resistant products. Cr is another carbide forming element. Most of these conventional carbide forming metals are, however, expensive and result in an inconveniently high priced product. Thus, there is a need within the powder metallurgical industry for a less expensive iron-based powder, or high speed steel, giving sufficient wear resistance to pressed and sintered products such as for valve seats or the like.
As chromium is a much cheaper and more readily available carbide forming metal than other such metals used in conventional powders and hard phases with high wear resistance, it would be desirable to be able to use chromium as principal carbide forming metal. In that way the powder, and thus the compacted product, can be more inexpensively produced.
The carbides of regular high speed steels are usually quite small, but in accordance with the present invention it has now unexpectedly been shown that powders having equally advantageous wear resistance, for e.g. valve seat applications, may be obtained with chromium as the principal carbide forming metal, provided that the carbides are large enough.